Screw jack mechanism



Filed April l0, 1929 INVENTCR Patented Jan. 26, 1932 UNITED STATES f.iJAi'riilai oFFlcE HAROLD `W. CLARK, F ALI`[.I.A1\TCE, OHIO, ASSGNCR TO THE BUCKEYE JACK MANUFAC- d 'DURING COMPANY, `O1? ALIlIiIANCE,` OHIO, A CORPORATION 0F OHIO SCREW JACK MECHANISM Application mea 'April 1o, 1929. serial N2. 353,954.

This invention relates to screw jack mechanism, and more particularly to a mechanism employed with lifting jacks of the double s screw type for controlling the rotation of I the screws employed.v

`In the British patent to Hill, No: 62 of '1857, there is illustrated a double screw jack comprising a standard havinga rotatable collar mounted thereon and effective for l0 raising and lowering a sleeve therein. A second screw is threaded into the sleeve and rotation of the collar lis effective for raising and lowering thescrews. It is desirable to elevate the `outer screw or sleeve first, and in my pending application Serial No. 322,644, showing a mechanism generally similar to that illustrated herein, there is described and claimed means for effecting this result. The present application constitutes an improvement on the invention of my said prior application. v

, In the accompanying drawings illustrating the present preferred embodiment of the invention, f v l Figure 1 is a vertical section taken through the jack and illustrating the lifting screws,

Figure 2 isa horizontal/section taken on the line II--II of-Figure 1,

Figure Sis a side' elevation, partly broken 30 away, of the lifting screws, and

Figure't isa horizontal section taken on rthe line IV-'IV of Figure 1.

The illustrated jack comprises abase 2 'havingan upstand-ing portion 3 with an inwardly turned flange l on which is mounted a ball b earing.` A nut 6 lies over the ball bearing 5 and carries a sleeve 7, which is preferably formed fr om a sheet of metal bent to tubular form. It is fastened to the 'm nut 6 by welds 8. The sleeve 7 has a bearing on theportion 3 of the base at 9 and 10, and

at its lower'end it carries a bevel gear 11 secured to the Vsleeve by welding, as indicated at 112.5`A bevel pinion 13 is 'journalled split ring 15.` The pinion is provided with i a socket 16 for the reception of a jack operating handle. It will benoted that when the pinionis in place the nut 6 is held securely against its bearing 5. The assembly and disassembly of the ack is therefore an extremely simple matter, the positioning of the pinion being alone relied on to; hold the parts inV place.

Vcontains the bearing balls 18. This bearing vmay be manufactured at very low 'expense' and the balls simply lie in the race 17 until the jack is assembled. After assembly the jack can be turned to any p'osition'without danger of the balls getting out of their race.

-IThe nut 6 is threadedto accommodate 'ai main lifting screw 19, whichfscrew itself is Ainternally threaded, to receive a secondary lifting screw 20. The secondary lifting screw 20'is providedwith a head 21 to engage the Aautomobile axle or other articlevwhich is to be lifted.`

The main lifting Ascrew 19 is prov1ded adjacent its bottom with a crosspin 22 adapted to engage ribs 23 on the inside of the base por- 1 tion 3 during the major portion of the lifting .movement of the screw. The engagement of the'pin 22 with the ribs 23 prevents rotation of the screw, whereby rotation of the nut i6 `causes the screw to be raised or lowered. Near the top of the lifting movement of the `of the nut 6 causes-the screw 20 to be threaded out of the screw 19.

The ribs 23 are terminated short of the bot- 130m of the jack so that the screw 19 may turn freely in its bottom position. This provision is made because there is no positive mechanism for insuring sequential retraction of the screws 19 and 20, and it may happen that the screw 20 will be partially extended when the screw 19 has reached its bottom position. In such cases it is necessary that the screw 19 be rotatable so as to thread the screw 2O back to its bottom position. As shown in Figure 1, the ribs 23 terminate at 24 and the pin 22 lies tlierebelow when the screw 19 is retracted.

The feature of the present invention is a ratchet mechanism for controlling the screw 19 when it is in this lowered position. The ratchet proper comprises a sleeve 25 which embraces the bottom portion of the screw 19 and is preferably bent up from sheet metal, as best shown in Figure t. The bottom end of the screw 19 is of reduced diameter as indicated at 26, so as to limit upward movement of the sleeve, and downward Amovement is limited by the pin 22 which engages shaped recesses 27 formed in the sleeve 25. The sleeve is further provided on its bottom edge with ratchet teeth 28 adapted to engage upstanding ribs 29 on the bottom portion of the base. i

During lowering of the jack, the bevel gear 11 with its connected parts is rotated counterclockwise, as viewed in Figure 2. If the screw 19 has reached its bottom position while the screw 20 is still extended, it is necessary that the screw 19 rotate counter-clockwise with the bevel gear 11. The ratchet teeth 28 are so inclined as to permit of this rotation and the j ack can therefore be actuated until the screw 2O is entirely retracted, without danger of the parts binding.

Now assume that it is desired to elevate the jack. The bevel gear 11 is rotated clockwise and the teeth 28 engage the ribs 29. The screw 19 tends to rotate with the nut 6, and this brings the pin 22 into engagement with inclined faces 30 of the recesses 27, resulting in a cam action which urges the sleeve downwardly and insures that the teeth 28 will continue to engage the ribs 29. The screw 19 being thus effectively locked against rotation, itis raised by the rotation of the nut 6, the ratchet continuing to engage the teeth 29 until the pin 22 has been `elevated a sufficient distance to engage the ribs 23.

I have illustrated and described a present preferred embodiment of the invention. It will be understoed, however, that it is not liniited to the form shown but may be otherwise embodied within the scope of the following claims.

I claim:

1. A jack comprising a base, a rotatable nut carried thereby, a lifting screw threaded in the nut and effective for lifting movement on rotation of the nut, means carried by the screw and engageable with the base for limiting rotation of the screw during the major portion of its travel, a lug on the base and a ratchet carried by the screw Cooperating with said lug for limiting rotation of the screw to one direction during another portion of its travel.

2. A jack comprising a base, a rotatable nut carried thereby, a lifting screw threaded in the nut and effective for lifting movement on rotation of the nut, means carried by the screw and engageable with the base for limiting rotation of the screw during the major portion of its travel, a lug on the base and a ratchet carried by the Iscrew cooperating with said lug for limiting rotation of the screw to one direction during another portion of its travel, the ratchet comprising a toothed sleeve embracing the screw.

3. A jack comprising a base, a rotatable nut carried thereby, a lifting screw threaded in the nut and effective for lifting movement on rotation of the nut, a pin carried by the screw and engageable with the base for limiting rotation of the screw during the major portion of its travel, a lug on the base and av ratchet carried by the screw cooperating with said lug for limiting rotation thereof to one direction during another portion of its travel, the ratchet comprising atoothed sleeve embracing the screw above the pin, the pin extending through the screw for limiting the downward movement of the sleeve relative to the screw.

4. A jack comprising a base, a rotatable nut carried thereby, a lifting screw threaded in the nut and effective for lifting movement on rotation of the nut, a pin carried by the screw and engageable with the base for limiting rotation of the screw during the major portion of its travel, a lug on the base and a ratchet carried by the screw cooperating with said lug for limiting rotation thereof to one direction during another portion of its travel, the ratchet comprising a toothed sleeve embracing the screw above the pin, the pin extending through the screw for limiting the movement of the sleeve, the sleeve having a portion shaped to engage the pin and urge the teeth of the ratchet to operative position.

5. In a lifting jack, the combination with hollow post on a base, a screw therein and a nut on the post for actuating the screw, of a pin on the screw and a rib on the post for locking the post against rotation during a portion of its movement, a toothed sleeve loosely mounted on said screw serving as a ratchet, and a lug on said base adapted to engage the sleeve for locking the screw when said pin and rib are ineffective.

6. In a lifting jack, the combination with a hollow post on a` base, a screw therein and a nut on the post for actuating the screw, of a. pin on the screw and a rib on the post for locking the post against rotation during a portion of its movement, a toothed sleeve loosely mounted 011 said screw serving as a ratchet, and a lug on said base adapted to engage the sleeve for locking the screw when said pin and rib are ineffective, said sleeve havno cam surfaces for engaging the pin Jshe eleeve effectively engages the lug until the pm engages the rib. y l

In testimony whereof I have hereunto set my hand. 0

HAROLD W. CLARK. 

